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101.
本文建立了2,2’-二羟基联苯(DHP)和4-羟基联苯(HP)的胶束增敏导数-可变角同步荧光同时分析方法,可变角同步扫描所得到的DHP和HP的谱峰位置均对应于常规光谱中的最佳激发-发射位置,经二阶求导后,消除分析谱带干扰,所得的二阶导数-可变角同步光谱即可用于两物质的同时测定,方法快速灵敏,DHP测定范围为0.05~0.5mg/L,HP测定范围为0.07~2mg/L。 相似文献
102.
用TREF方法分离聚烯烃共混物 总被引:1,自引:0,他引:1
用TREF方法分离聚烯烃共混物徐君庭,封麟先,杨士林(浙江大学高分子科学与工程学系,杭州,310027)关键词升温淋洗分级,聚烯烃,共混物升温淋洗分级(TREF)方法是80年代发展起来的,它按结晶度将聚合物分级[1],目前主要用于聚烯烃的分级[2,3... 相似文献
103.
A novel instrumental technique for the direct, fast, accurate, and precise determination of uranium in concentrates and other U-rich materials (as well as to mineralized rocks) is presented. The proposed technique is an absolute methodology, based on the comparison of the fluorescence of the accurately known standard with a sample of similar but unknown concentration in the low operational range of the instrument (on same sample-dilution basis), by the use of H3PO4-NH4H2PO4 as a fluorescence-enhancing reagent. The relative standard deviation of the proposed technique was 0.5-0.9% (n=9) at 18.1, 36.2, 61.2, and 99.6% U3O8. The proposed technique is suitable for the determination of uranium in samples arising from exploration projects, ores from mining operations, mill process samples, uranium ore concentrates leading to fuel fabrication as well as samples from environmental monitoring containing up to 100% uranium. The results are in good agreement with those obtained by titrimetric, gravimetric, and TBP extraction-H2O2 spectrophotometric methods. The precision of the technique is within the acceptable ‘pure geochemistry’ type of analysis (R.S.D. ∼ 1.0%) and is comparable even those obtained with titrimetric and gravimetric assay. The proposed differential technique coupled with flow injection may open up new advancement in instrumentation leading to design and development of microchemielectronic devices for direct on-line determination, more compatible with the tools of computer age as also to help in handling of radioactive solutions in chemical laboratories in uranium processing industries. 相似文献
104.
The methylation of tin(II) [Sn(II)] by iodomethane (CH3I) under environmental conditions has been further demonstrated by a 13C carbon isotope tracer method. Methylation products are mainly monomethyltin, and very small amounts of dimethyltin. The reaction of Sn(II) and CH3I was investigated at pH 2, 4, 6, 8, 10 and salinity (S) 8, 15, 22, 28, 35%; it has been found the reaction was affected by pH and salinity, the tin methylation activity being highest at about pH 6 and S = 28% . The methylation reaction is first-order for both CH3I and Sn(II), and the rate equation has been obtained as follows: . 相似文献
105.
利用等温和非等温方法详细研究了芳香族聚酯──热致型聚合物对,对’-联苯二甲酸二辛酯的结晶相和液晶相形成机理,并计算了相变过程中的表面自由能与温度系数,研究结果表明:从介晶相开始的结晶过程是二维异相成核、三维线性增长的,而从各向同性液相开始的液晶相形成过程则是二维异相成核二维线性增长的.对两个晶化过程的表面自由能的研究表明,该聚合物液晶相形成过程的相转变表面自由能比结晶过程小得多,预示了它将具有更大的晶化速率.研究还发现,该聚合物的液晶相形成过程具有比结晶过程大得多的温度敏感性. 相似文献
106.
Electrostatic interactions of proteins, including bovine serum albumin (BSA), human serum albumin (HSA), γ-globulin (γ-IgG), α-chymotrypsin (Chy), lysozyme (Lys) and cellulase (Cel), with multiply negatively charged chromophores were investigated based on the measurements of the enhanced resonance light scattering (RLS) signals. Using triply negatively charged water blue (WB) as an example, the factors were discussed that affect the enhanced resonance light scattering signals of the interactions between proteins and the negatively charged chromophores. It was found that the enhanced RLS signals with the maximum light scattering peak at 346.0 nm in these interacting systems are strongly dependent on the isoelectric points of proteins and show adverse linear relationships with increasing ionic strength depending on the positive charges of the inorganic metal ions used to control the ionic strength of the medium, sufficiently disclosing that the electrostatic attraction performs an important role in the combination of proteins with WB. Linear responses were discovered between the enhanced RLS signals and the protein molecular weights (Mw), displaying the dimensions of scattered particles formed by proteins and WB make a key contribution to the RLS enhancements. An empirical equation is proposed which possibly displays the factors affecting the enhanced RLS signals of the interactions between proteins with negatively charged chromophores. 相似文献
107.
Lämmerhofer M 《Journal of chromatography. A》2005,1068(1):31-57
A review on the advantages, peculiarities, and the potential of enantioselective capillary electrochromatography (CEC) in nonaqueous media is presented. Some fundamentals on CEC with particular focus on enantioselective CEC are discussed. The strategies, concepts, preferentially utilized chiral selectors and column technologies that have been utilized to succeed in highly efficient enantiomer separations by nonaqueous CEC are described thoroughly. 相似文献
108.
A solvent venting technique for injection of volumes up to 1 μl on 50 μm i.d. SFC columns has been compared to direct injection methods. The peak broadening and peak splitting observed with direct injection have been examined and found to be related to the starting pressure, the column temperature, and the sample solvent, in addition to the sample volume. The solvent venting technique removed peak splitting and improved the column efficiency. With a proper selection of experimental conditions, the sample recovery was 100%. The major part of the solvent was eluted in 15–20 s. Several applications have been demonstrated. 相似文献
109.
110.